The present invention relates in general to an anti-theft apparatus or circuit for an automobile. More particularly, this invention is concerned with an anti-theft circuit for use in a vehicle having an electrically operated fuel system such as a vehicle operated by a fuel injection system.
My U.S. Pat. No. 3,968,666 shows a circuit for controlling the operation of the vehicle by interrupting the fuel flow to the carburetor by operation of a solenoid or relay. This prior art circuit includes a concealed switch only known to an authorized operator and which, when closed, permits normal operation of the vehicle. This circuit is adapted for use primarily with a fuel system employing the conventional mechanically operated fuel pump and carburetor. One of the advantages to this known circuit is that once the unauthorized person has by-passed the ignition switch, the vehicle will actually start because there is some fuel in the fuel pump, carburetor and interconnecting lines. However, the unauthorized operator will be able to travel only a relatively short distance and usually the vehicle ceases operation in a location where the unauthorized operator has no other alternative other than to abandon the vehicle as quickly as possible. However, with a fuel injection system a circuit of the type shown in U.S. Pat. No. 3,968,666 will not permit even a slight operation and motion of the vehicle because the electrically operated fuel system requires immediate electrical control for operation thereof. Because the vehicle will not start at all the thief is immediately alerted to the apparent presence of an anti-theft circuit, and may then be able to trace the location of this circuit to by-pass the circuit. On the other hand, if the vehicle had started and moved a relatively short distance then the thief would most likely be in a disadvantageous position to continue any further investigation as to the inoperability of the vehicle.
Accordingly, an object of the present invention is to provide an anti-theft apparatus or circuit for controlling the operability of an electrically-operated fuel system for a vehicle.
Another object of the present invention is to provide a control circuit in accordance with the preceding object that operates to permit temporary operation of the vehicle when entered by an unauthorized operator. In accordance with the present invention the timing network comprises a part of the anti-theft circuit and when an unauthorized person enters the vehicle not being aware of the presence of a concealed enabling switch, the timing network times-out and the operation of the fuel-system then is interrupted.
Another object of the present invention is to provide a bypass switch associated with the anti-theft circuit essentially by-passing the timing network and concealed switch. This arrangement is used, for example, when the authorized operator leaves the vehicle with an attendant at a parking lot.